Sg V is a 212 amino acid protein that is secreted by endocrine and neuroendocrine secretory granules and belongs to the 7B2 family. Existing as two alternatively spliced isoforms, Sg V interacts with PC2 and, via this interaction, functions as a molecular chaperone for PC2, effectively preventing its premature activation in regulated secretory pathways. More specifically, Sg V binds to PC2 and facilitates its transport from the endoplasmic reticulum to secretory compartments, thus allowing PC2 to be cleaved and activated during the correct phase of the regulated secretory pathway. Sg V is subject to post-translational sulfation on specific tyrosine residues and is underexpressed in medulloblastomas, suggesting a role in tumor suppression. The gene encoding Sg V maps to human chromosome 15, which houses over 700 genes and comprises nearly 3% of the human genome.